Like most of you, I've always wanted want to code and compile 68k Mac OS applications in OS X that work on System 1.1. This question kept me up night after night, but thanks to Steven Troughton-Smith, we now know that it is, indeed, possible. It started with a 68k application on System 6. Not long after, he managed to compile a simple application that worked on System 1.1. This test application's code is available on github.